Carbonic acid esters



Patented June 2c, 1945 'uu 'rso s'rAras PATENT ori ice I 2,319,252

oannourc Acmns'raas 4 Irving a. Muskat, Norton Center, Ohi

Simon, and Franklin Strain,

o, assignors to Pittsburgh Plate Glass Company, Pittsburgh, Pa., a corpovania ration of lfennsyl No Drawing. Application October 4, 1941,

- Serial No. 413,644

5 Claims. (01. 261F463) I This invention relates to a novel class or compounds which have been. found to have many desirable properties. In accordance with themesent invention, we have prepared a novel class 0! esters which are esters ,of (a) an ether alcohol which contains one or more ether-linkages between a pair of hydroxyl groups and (b) a half ester of carbonic acid and a saturated alcohol.

The invention is particularly directed to esters oi polyslycols, particularly of the alkylene glycols such as di-, tri-, tetra-, penta-, or hexaethylene glycol, di tri-, or tetra-propylene'glycol, dibutylene glycol, tributylene glycol, or the polyglycols o1 trimethylene glycol, or pentamethylene glycol, etc., In addition. esters of other ether alcohols such as polys cerols, dioxane diols such 'as lA-dioxane dim-2,3, or the compound or the corresponding ether alcohols derived from the higher alcohols including methyl glycerol,

' in parenthesis. Such compounds ingeneral con-- Rs in each molecule of the hydroxy ether molecule which a: hydroxy roups are esteriiied with the radical indicated tain a single radical compound. I

In the case of the monoesters'the remaining hydrorgyl group or groups may be free or etherlfled or esterified by other acids, for example, acetic, butyric, stearic, oleic, acids,-etc. monomethyl phthalate, monomethyl succinate, mono-i .methyl adipate, or alcohols such as methyl, ethyl, allyl, propyl, methallyl, oleyl, or ,lauryl alcohols. etc. Such monoesters'may be prepared, for example, by reacting a monohydroxy ether or mannitol, etc. may be prepared. Moreover, es-

' ters of poly ydroxy aromatic ethers such as DJ dihydroxy diphenyl ether, bis (hydroxy benzyl) ether, or hydroxy cumaron, etc. may be prepared. 26

The compounds herein contemplated may be esters of various saturated monohydric alcohols such as methyl, ethyl, propyl, butyl, amyl, hexyl, lauryl, or stearyl alcohols or secondary or tertiary alcohols such as secondary or tertiary butyl alcohols, isopropyl alcohol, pentanol-3, pen'taol-3, or

aromatic or araliphatic alcohols such as p-phenyl ethyl alcohol, benzyl alcohol, phenyl methyl carbinol, cyclohexanol, cyclopentanol, or the halogen or other substitution products of the above alcohols. such as chloromethyl, chloropropyl, chlorobenzyl, or chlorobutyl alcohols. In addition, esters may be prepared from etherv alcohols containing a single alcoholic hydroxyl group suchas the mono ethyl ether of ethylene glycol, the monomethyl ether of ethylene glycol, or other alkenyl or alkynyl or other corresponding alkyl ethers such as propyl, butyl, lauryl, allyl, pro.-'

D yl, methallyl, oleyl, phenyl, etc., or the corresponding mono ethers oi other glycols such as the propylene or butylene glycols or theabove mentioned polyglycols.

Both polyesters and monoesters of these polyslrcols may be prepared. Thus, the compounds will have a general formula:

in which RA is the radical derived from a saturated alcohol and RE is the portion of the polyester of a poly col with a chloroiormat'e or a saturated alco ol. Suitable monohydroxy ethers are the monoacetate or diethylene glycol, dipropylene lycol monoacetate, triethylene' glycol monoacetate, etc., and the co espondin'g acrylates, propionates, oleates, bu tes, stearates, propiolates, etc., the monometh l ether of dieth-.. 'ylene glycol, or-the corresponding monoamyl,

in which RA is the radical derived from saturated R and Rn-H. are the hydrocarbon or substituted hydrocarbon radicals of alcohol and R1 which the polyhydroxy ether is constituted;

. The polyesters may be prepared by reaction of the iiichloroiformate of the polyglycol such as diethylene glycol dichloroi'ormate with the desired alcohol. Both mono and-polyesters may be.

prepared by reaction of the chloroformate of the alcohol with the polyglycol. 'In general, substantially theoretical amounts of the, reactants are used in the production of the various esters. The reaction may be promoted by the presence of an alkaline reagent. For this purpose, organic bases such as trimethylphenyl ammoniumhydroxide or inorganic bases such as the oxides, hydroxides, and carbonates of sodium, potassium, calcium, barium, strontium, and magnesium or other alkaline earth metal, or alkali metal are useful. The alkaline agent nifbe inSOlll'tiOh or may be dispersed as a finely pulverized solid material.

r polyhydroxy ethers (cap I Thus, finely divided calcium carbonate has been found to be eflective.

Water may be present or the reaction may be conducted under substantially anhydrous conditions. It may, under some circumstances, be desirable to add diluents such as water, acetone, carbon tetrachloride, or dioxane.

The temperature of the reaction will depend upon the nature of the alkaline reagent used.

when pyridine or caustic soda is used, temperatures less than normal room temperature (15- 25 C.) may be used since such lower temperatures generally favor higher yields. -When calcium carbonate is used as the alkaline reagent, it is desirable to'operate at higher temperatures, preferably above 50 C. The eifect of reduced yields can be compensated by controlling the concentration of reactants, thus, by using an excess of both alcohol and alkaline reagent, almost quantitative yields can be obtained in many cases. When operating under such circumstances, the excess of reagents may be recovered and used in subsequent preparations.

The esters are generally high boiling liquids although in some cases they may be solids. The liquids are particularly interesting since they have very high boiling points and yet possess very low viscosities. They are compatible with many organic solvents such as acetone, ethyl alcohol, xylene, toluene, benzene, chloroform, etc. They are, in general, substantially insoluble in water. Most of these liquids are colorless and possess a faintly sweet odor.

These compounds herein described are capable of wide use as solvents and plasticizers. They are found to be particularly eflective as plasticizers for synthetic resins and plastics such as cellulose esters or ethers including cellulose acetate, nitrate or acetobutyrate, ethyl or methyl cellulose, vinyl resins including vinyl acetate, vinyl chloride, styrene, and acrylic polymers or thebutadiene polymers such as copolymers of butadiene with various materials such as styrene or acrylonitrile. Synthetic rubber compositions of this type plasticized with these esters may be vulcanized at an elevated temperature without loss of plasticizer or formation of a bubbled or a porous product due to vaporization of the plasticizer. Y

The following examples are illustrative:

Example I v A 25 percent excess of 50 percent sodium hydroxide (634 gms.) was sprayed into a rapidly stirred mixture or 732 gms. of diethylene glycol bis chloroformate and 586 gms. of n-butyl alcohol. The temperature was maintained between 15 and 20 C. by cooling. The sodium hydroxide was added over a period of 35 minutes and after the addition was completed the mixture was stirred for on hour. The ester was washed with one liter of water and heated to 150 C. at 15 mm. with 1 gram of activated charcoal for one-half hour. The diethylene glycol bis (n-butyl carbonate) was distilled at 175-180 C. at 3 mm. total pressure. The material was found to have a density of about 1.097 at 20 C. and an index of refraction of about 1.4470.

dichloroformate, ,120 gms. or n-propyl alcohol,

1000 cc. ofbennene and 150gms. of finely divided calcium carbonate was placed in stwoliter desk. The mixture was-refluxed for two hours. The resulting ester was washed with dilute NaaCoa solution and with water and finally dried over NaaSOr. The triethylene glycol bis (propyl carbonate) was decolorized by heating with activated charcoal and was purified by distillation. A colorless liquid was secured.

Example In A mixture of 130 gm. of dipropylene glycol and 200 gms. of pyridine was cooled to 0 C. on an ice bath. 200 gms. of ethyl chloroformate, prepared by reacting ethyl alcohol with phosgene, was added slowly at a rate which permitted the temperature to remain below 1010. The reagents were completely mixed in one hour. After removing from the ice bath the mixture was allowed to stand for two hours. The ester was washed with water and distilled with 1 gram of activated charcoal. The ester is a colorless liquid having the following probable structure:

ouzro- -o-cm-t m,

Example IV which boils at about 140-148 C. at 3 millimeters of mercury and has a density of about 1.244 at 20 C. and an index of refraction of about 1.4370.

Example V The procedure of Example I was used except butyl cellosolve was used in place of n-butyl alcohol. The ester thus obtained had a boiling point of about 240-260" C. at 2 mm., a density of about 1.072 at 20' C. and an index of refraction of about 1.4405. This ester is a colorless liquid having the following probable structure:

o om-onr-cHr-onr-o-omr-o-ao-Lmi Example VI 1 can-o-csn-o-ti-oin.

The following table sets forth the approximate goveaoe v boiling point of a number of the esters herein con} templated: v y 7 Boiling point Compound Teigp Pressure mm. Hg

Diethylene glycol bis (ethyl carbonate) 138-148 2 Diethyleno glycol bis (n-propyl carbonate). -155 2 Diethylene glycol bis (n-amyl carbonate) -185 2 v Dlethylene glycol bis (butyl cellosolve carbonat 240-260 1 2 Diethylene glycol bis (Z-chloroethyl carbona -190 2 v Diethylene glycol bis (tetrahydrol'urluryl car- I bonate) 240-250 1 2 I Decomposes during distillation.

This invention is a. continuation-in-part of copending application Serial No. 385,772, flied March 28, 1941, by Irving E. Muskat and Franklin Strain.

' hydroxy groups Although the invention is described with respect to certain specific details, it is not intended that such details shall be limitations upon the scope of the claims except as following claims. y We claim:

1. A neutral diester of (a) a polyglycol and (b) two molecules of an acid ester of carbonic acid and a saturated aliphatic alcohol.

2. A neutral diester of (a) a. polyethylene glycol and (.b) an acid ester-of carbonic acid and a saturated aliphatic alcohol said ester having both of the glycol esterified with the acid-ester. t

3. Diethylene glycol bis (ethyl carbonate) 4. Trlethylene glycol bis-'(ethylcarbonate).

5. Triethylene glycol Ibis (butyl carbona.te).

-IRVING1E. MUSK A'll FRANKLIN STRAIN.

expressly included in the 

